Dietary l-carnosine supplementation has been shown to enhance animal performance and improve meat quality. However, the mechanisms underlying the effects of l-carnosine on the physiological functions of animals have not been fully elucidated. We investigated the effects of dietary l-carnosine supplementation on growth performance, intestinal microbiota diversity, and the serum metabolome in fattening lambs to reveal the molecular mechanism underlying the effect of l-carnosine on the growth performance of sheep. Sixty 3-month-old male crossbred lambs (Dorper ♂ × Small Tail Han ♀) with an average body weight of 30 ± 5 kg were randomly divided into two groups: a control group (group C) fed a basal diet, and an experimental group (group L) fed a basal diet supplemented with 400 mg/kg of l-carnosine. At the end of the 60-day experiment, all sheep were weighed, and fecal and blood samples were collected from 12 random sheep. The fecal microbiota was analyzed using 16S rRNA sequencing, and serum metabolites were analyzed using liquid chromatography–tandem mass spectrometry. Spearman correlation analysis was employed to assess the associations between intestinal microbiota and serum metabolite biomarkers. The results showed that weight gain and daily weight gain were significantly increased in group L compared to group C (p < 0.01). The dominant phyla in the intestinal microbiota (Firmicutes and Bacteroidetes) did not significantly differ between the two groups (p > 0.05). At the genus level, the abundances of Syntrophococcus (p < 0.01) and Butyricimonas (p < 0.001) were higher, whereas those of Escherichia-Shigella and Candidatus Saccharimonas were significantly lower in group L than in group C (p < 0.05). Non-targeted metabolomics identified 68 differentially abundant biomarkers (VIP > 1, p < 0.05). The content of pyridine N-oxide glucuronide was significantly downregulated (p < 0.01), whereas those of l-histidinol, d-apiose, and isodomedin were significantly upregulated in group L versus group C (p < 0.001). Holdemania and Butyricimonas were positively correlated with l-histidine, d-apiose, and l-erythrulose (p < 0.001), whereas Butyricimonas was negatively correlated with pyridine N-oxide glucuronide (p < 0.001). This study provided new insights into the effects of l-carnosine on the intestinal microbiota and nutrient metabolism in fattening sheep that will be helpful for the future application of l-carnosine in ruminants.

The Northwest Xizang White Cashmere goat has a high global reputation for good goat cashmere germplasm characteristics, and its cashmere industry is the economic pillar of the herdsmen in the northwest plateau of Xizang. Cashmere is produced by the secondary hair follicles of the skin, and the key period of hair follicle development is from birth to 3 months old. This study aimed to explore how early compound nutritional intervention affects lamb growth performance and secondary hair follicle development. We assessed skin follicle density and performed skin transcriptomic and multi-omics analyses to clarify this regulatory effect. The trial was performed at the Northwest Xizang White Cashmere Goat Breeding Farm, Ritu County, Ngari region, Xizang. Thirty newborn single lambs of comparable birth status were randomly divided into control and early compound nutritional intervention groups (n = 15 per group). The results showed that early compound nutritional intervention significantly increased the secondary hair follicle density, total hair follicle density, and secondary/primary hair follicle (S/P) value of lambs (p < 0.05). However, there was no significant difference in the average cashmere fineness between the two groups (p > 0.05). The transcriptome, proteome, and metabolomics analyses of the skin revealed candidate genes related to hair follicle development and the regulation of cashmere fineness: keratin structural genes (KRT10, KRT18, KRT26), cell proliferation and adhesion-related regulatory genes (ITGB2, CSF1R, AKT1), and extracellular matrix coding genes (COL6A1, COL6A2, COL6A6). Moreover, the results revealed that key proteins related to hair follicle development include RBP4, KAP13-3, KRTAP3-1, KRTAP27-1, DKK3, ITGB2, and DUSP23. The differentially expressed metabolites, 15-Deoxy-delta12,14-Prostaglandin J2 and Thromboxane B2 (TXB2), modulate prostaglandin-associated pathways; altered pathway activity subsequently regulates the expression of hair follicle functional genes and key proteins, which may in turn indirectly regulate hair follicle growth and development, thereby affecting hair follicle density and, by extension, cashmere production performance. Therefore, early compound nutritional intervention of Northwest Xizang White Cashmere goats promotes the growth and development of secondary hair follicles. The identified candidate genes and key proteins involved in secondary hair follicle development provide a reference for exploring the mechanism of hair follicle development.

This study aimed to investigate the effects of Yucca schidigera extract (YSE) on growth performance, serum immune parameters, rumen microbiota, and metabolites of fattening goats. For this purpose, thirty-two healthy male Boer goats with similar initial body weights (36.91 ± 3.05 kg) were randomly assigned to four groups. Goats in the control group (Group A) were fed a basal pelleted diet, whereas the experimental groups (Groups B, C, and D) received 200, 400, and 600 mg of YSE per kg of basal diet, respectively. The results reveal that dietary supplementation with 600 mg/kg YSE significantly elevated average daily gain (ADG) and decreased feed-to-gain ratio (F/G) (p < 0.05). The 400 mg/kg YSE addition significantly increased serum IgM concentration and reduced the TNF-α concentration (p < 0.05). Meanwhile, 400 mg/kg dietary YSE supplementation significantly elevated Ace and Chao-1 indices of ruminal microbiota (p < 0.05). Differential ruminal metabolites were predominantly enriched in pathways involving pantothenate and CoA biosynthesis, regulation of lipolysis in adipocytes, thermogenesis, and lysine degradation. Prevotellaceae_UCG-001 was negatively correlated with average daily feed intake (ADFI) and immunoglobulin M (IgM) (p < 0.05), and ascorbate radical and ureidoperacrylic acid showed significant correlations with ADFI, IgM, and Prevotellaceae_UCG-001 (p < 0.05). Both Anaerobispirillum and Quinella were negatively correlated with TNF-α (p < 0.05), whereas thiamine and zeatin showed positive correlations with TNF-α and Quinella (p < 0.05). Under the present experimental conditions, the optimal supplemental level of YSE was 400 mg/kg diet.

A total of 160 healthy raccoon dogs with no significant difference in body weight were selected and randomly divided into 10 groups, with each group having 4 replicates and each replicate consisting of 4 individuals. The pre-test period lasted for 7 days, followed by a formal test period of 82 days. The raccoon dogs in the 10 groups were fed basal diet supplemented with 50 mg/kg chlortetracycline and 100 mg/kg quinocetone (control group), 100 mg/kg OEO and 150 mg/kg BS (group I), 100 mg/kg OEO and 300 mg/kg BS (group II), 100 mg/kg OEO and 450 mg/kg BS (group III), 200 mg/kg OEO and 150 mg/kg BS (group IV), 200 mg/kg OEO and 300 mg/kg BS (group V), 200 mg/kg OEO and 450 mg/kg BS (group VI), 300 mg/kg OEO and 150 mg/kg BS (group VII), 300 mg/kg OEO and 300 mg/kg BS (group VIII), 300 mg/kg OEO and 450 mg/kg BS (group IX). The results showed that there were no significant difference in final weight and average daily gain among all groups (P > 0.05). The ADFI of group IV was the least, which was significantly lower than that of the control group (P < 0.05). The F/G in group IV was significantly higher than that in groups I, II, III, V, VII and VIII (P < 0.05). There were no significant differences in DM output, DM digestibility, protein digestibility and fat digestibility among groups (P > 0.05). There were no significant differences in nitrogen intake, fecal nitrogen, urine nitrogen, nitrogen retention, net protein utilization rate and protein biological value among the ten groups (P > 0.05). There was no significant difference in serum SOD activity, GSH-PX activity, MDA content and T-AOC activity between the groups supplemented with OEO and BS compared with the antibiotic group (P > 0.05). There was no significant difference in body length, skin length, skin weight, guard hair length and underfur length between each level group and the control group (P > 0.05). The feed input cost of the other experimental groups was lower than that of the control group except for the experimental groups II, VIII and IX. The cost of feed additives in each experimental group was higher than that in the control group. The income of group III, VII and IX was higher than that of the control group, and the income of group III was the highest. In conclusion, under the experimental conditions, dietary supplementation of OEO and BS to the diet can improve the growth performance, fur quality as well as absorption of nutrients and antioxidant level by the body of raccoon dogs in winter fur period. The optimum supplemental levels of OEO and BS in the diet of raccoon dog in winter fur period were 100 mg/kg and 450 mg/kg.